1. Field of the Invention
This invention relates to an SOHC internal combustion engine, and particularly to an improvement in an SOHC internal combustion engine in which a protecting cylinder having an ignition plug insertion hole is provided adjacent to an ignition plug mounting hole which opens in a center portion of the top surface of a combustion chamber of a cylinder head, and a cam shaft journal having a diameter larger than the path of the rotation of the tip of a cam nose is received in a bearing hole in a cam shaft receiving wall which is projectingly provided in the cylinder head.
2. Description of the Prior Art
Conventionally, an internal combustion engine in which a protecting cylinder is provided between a pair of cam shaft receiving walls is known. (Japanese Patent Kokai No. 125315/1979)
The rigidity of the cam shaft receiving wall and the protecting cylinder tends to be low because the cam shift receiving wall and the protecting cylinder project individually from the cylinder head.